I love r because it's a good-looking letter of the Greek alphabet. I also love r because it was invented by my good friend Dave N. Lee, long before we met. In fact, it was very nice of him to immortalize this measure, presciently, using Greek in 1976 (Lee, 1976), some 12-odd years before our acquaintance was made in 1984 in Beilefeld, Germany. At the time, we spent the whole night musing over tau with Claes Von Hofsten and Dave over a bottle of decent single malt. That night also clinched a lifelong friendship with Dave and Claes, and an ongoing collaboration with Dave for the past 15 years.